What are the functions of lipids

Role of the lipids

Energy suppliers

Lipids (fats) have a very high physiological calorific value of 37 to 39 kJ / g, which is more than twice as high as carbohydrates or proteins (approx. 17 kJ / g each).

This high energy density also explains why lipids are preferably stored in special storage tissues as energy stores. The fatty tissue is not only a good energy store for times of need, but also protects internal organs and cushions us well against external mechanical influences.

Building blocks of cell membranes

Each cell membrane consists of a double layer of lipids in which various proteins are then stored. Most of these lipids are phospholipids and glycolipids, but cholesterol is also an important part of the membranes. Neutral fats tend to be less common in biomembranes; they are mainly used for energy supply.

But not only the cell membrane is made up of lipids, but also the membranes of the cell organelles, for example the membranes of the mitochondria, the Golgi apparatus, the cell nucleus and so on.

Starting substance for active ingredients

Important active ingredients of the body are synthesized from certain lipids, the eicosanoids in particular are to be mentioned here. This refers to tissue hormones that have many different tasks in the body such as controlling blood clotting, immune reactions, etc.

Insulating layer / protective function

As already mentioned above, the fatty tissue is a "cushion" for the internal organs and also a good protection against external mechanical influences. For example, without fatty tissue on the buttocks, we would not be able to sit in a chair for long periods of time.

Thermoregulation

Layers of fat in the skin are natural heat insulators.

Carrier of fat-soluble vitamins

The fat-soluble vitamins E, D, K and A are only absorbed by the body when they "arrive" together with fat. That is why we should always eat our carrots (vitamin A) with a little butter, which also tastes better.

Carrier of essential fatty acids

Besides glycerine, fatty acids are the building blocks of lipids. Some fatty acids are starting materials for active ingredients (see above), and since pure fatty acids are hardly found in food, we have to eat fats in order to get to these essential fatty acids.

Flavor carrier, satiety function

Many aromas and flavors are fat-soluble, which is why many dishes taste much better if they are prepared with butter, margarine or oil. In addition, high-fat foods fill you up faster than low-fat foods.

More functions

Hahn, Ströhle and Wolters mention other functions of lipids in their book, about which one usually does not find anything in normal school books:

Cell compartmentalization

Lipids are components of all membranes, not just the cell membrane, but also the membranes that surround the compartments of the cell (mitochondria, ER and so on).

Neural excitation conduction

The myelin sheath of nerve cells contains a large number of lipids. The typical properties of lipids (hydrophobic) isolate the axons of the nerve cell from each other so that no electrical short circuits occur.

Anchor function

This means that many membrane lipids are a kind of anchor for other compounds that are in contact with the membrane.

Surface detection

Above all, glycolipids, i.e. lipids that are linked to sugar molecules, are found on the outside of the cell membrane of many cells. The body's own cells such as red blood cells have a specific "fingerprint" that the immune system recognizes.

Cellular communication

Some lipids act as primary or secondary messenger substances inside and outside the cell.

Endocrine function

Some important hormones are derived from cholesterol, especially the sex hormones estrogen and testosterone.

Anti-inflammatory / anti-inflammatory function

Long-chain fatty acids with 20 or more carbon atoms are the starting materials for certain active ingredients, the eicosanoids, which promote inflammatory reactions. Omega-3 fatty acids produce anti-inflammatory eicosanoids, while omega-6 fatty acids produce anti-inflammatory eicosanoids.